1. Field of the Invention
The present invention relates to a propeller shaft having a vibration controlling member made up of a paper tube within a propeller tube.
2. Description of the Background Art
In the event that gear meshing noise is transmitted to a propeller shaft which transmits the driving force of an engine of an automobile from a transmission or transfer to driving road wheels, a thin cylindrical propeller tube which makes up a main body portion of the propeller shaft resonates to thereby produce resonant noise when the frequency of the meshing noise coincides with the resonance frequency of the propeller tube.
In order to suppress the resonant noise, in a propeller shaft described, for example, in Japanese Patent Unexamined Publication No. JP-A-1-148621, a vibration controlling function is designed to be obtained by inserting a paper tube made by winding a thick paper into a cylindrical shape into the interior of a propeller tube as a vibration controlling member, so that the paper tube is brought into close contact with an inner surface of the propeller tube by virtue of a restoring force produced in the paper tube by virtue of the elasticity of the thick paper so as to suppress resonance by virtue of the close contacting force. In addition, in a propeller shaft described in Japanese
Utility Model Examined Publication No. JP-UM-B-2601067, the vibration controlling function is designed to be enhanced compared with a case where the paper tube comprises a single round or layer of thick paper by making a paper tube by winding a thick paper a plurality of rounds, so that a top layer of thick paper is strongly pressed against an inner surfaced of a propeller tube by virtue of the restoring force of second and third layers of thick paper so as to enhance the close contacting force.
Incidentally, in the aforesaid conventional propeller shafts, since the vibration controlling member which suppresses the resonance of the propeller tube is made up of the paper material whose weight is light, there is provided an advantage that the weight of the propeller shaft is suppressed to a small level. However, since the paper tube made by winding the thick paper into the cylindrical shape is not necessarily formed into a round, when the paper tube so made is inserted into the propeller tube, there is caused a problem that a gap is produced between an inner surface of the propeller tube and an outer surface of the paper tube. In addition, in the paper tube made by winding the thick paper the plurality of rounds, when an inertial force is exerted on the paper tube in an axial direction thereof at the time of abrupt start or stop, there occurs a case where an axial end of the paper tube constituting a start of winding deviates axially from the axial end thereof which constitutes an end of winding. When the deviation occurs, the outside diameter of the paper tube tapers as shown in FIG. 7, whereby there is caused a problem that the paper tube is separated from the inner surface of the propeller tube at the end thereof where the outside diameter is reduced or the weight balance of the propeller tube is lost due to a change in the shape of the paper tube to thereby deteriorate the vibration controlling function.